Perfluoro-3-methyl-2-pentene, its preparation and use

Abstract

The application discloses perfluoro-3-methyl-2-pentene and a preparation method and application thereof, and the preparation method comprises the following steps: heating tetrafluoroethylene to perform tetrafluoroethylene trimerization under the action of a catalyst, and after the reaction is completed, the obtained gaseous product is condensed and rectified to obtain perfluoro-3-methyl-2-pentene; wherein the catalyst is a fluorinated salt catalyst. The fluorinated salt catalyst is preferably a fluorinated quaternary ammonium salt catalyst or a fluorinated chlorinated salt catalyst. The application adopts the fluorinated salt catalyst with higher catalytic activity, especially the fluorinated quaternary ammonium salt catalyst to catalyze tetrafluoroethylene to perform tetrafluoroethylene trimerization, and through controlling the reaction conditions, the conversion rate of tetrafluoroethylene and the selectivity of perfluoro-3-methyl-2-pentene are both higher. Compared with general tetrafluoroethylene oligomerization methods, the application has the advantages of high perfluoro-3-methyl-2-pentene yield, long service life of the catalyst, no solvent, less waste, simple operation and the like.

Description

Technical Field

[0001] This invention relates to the field of fluorochemical technology, specifically to perfluoro-3-methyl-2-pentene, its preparation method, and its applications. Background Technology

[0002] Internet data centers are hardware facilities used to store internet data, and they consume a great deal of energy. Heat dissipation accounts for a significant proportion of power consumption within data centers. To save on cooling costs, many international internet giants build their data centers in relatively cold environments. As data centers develop towards larger scales and higher densities, high energy consumption and intense heat dissipation have become unprecedented challenges, and traditional air-cooling technologies are no longer sufficient.

[0003] Liquid cooling technology has become a revolutionary solution to the heat dissipation problem in data centers. The demand for liquid-cooled data center coolants is substantial, and it is projected that the demand will reach tens of thousands of tons in the next 3-5 years. As market requirements for fluorinated liquids become increasingly stringent in terms of price and environmental impact, fluorinated liquids are evolving towards lower GWP and lower prices.

[0004] Currently, the main types of immersion coolants on the market are hydrocarbon-based (mineral oil, etc., with advantages such as low volatility, low price, and environmental friendliness; disadvantages include flash point, flammability, low chemical stability, decomposition products that corrode equipment, and high viscosity), organosilicon-based (cetyl polydimethylsiloxane, with advantages such as good temperature resistance, stability, and contact safety; disadvantages include high viscosity, poor fluidity, flash point, and residue after evaporation), and fluorocarbon-based (hydrofluoroethers, perfluoropolyethers, fluorinated olefins, and perfluoroamines, with advantages such as no flash point, non-toxicity, low viscosity, and no residue after evaporation; disadvantages include high cost and high GWP values ​​for some types). Fluorocarbon compounds are currently the mainstream immersion coolants.

[0005] Among these fluorocarbon products, hydrofluorosaturated compounds (such as hydrofluorocarbons and hydrofluoroethers) have high dielectric constants and high GWP values; hydrofluorounsaturated compounds (hydrofluoroolefins and unsaturated hydrofluoroethers) have high dielectric constants but lower insulation properties; perfluorinated saturated compounds (such as perfluoroalkanes, perfluoroamines, and perfluoropolyethers) have relatively high GWP values. Only perfluorinated unsaturated compounds can balance low dielectric constants, good insulation properties, and low GWP values. Currently, perfluoroalkenylamines and perfluoroalkenyl ethers are difficult to synthesize and have high costs, while perfluoroolefins have the advantages of easy synthesis and low cost. Therefore, perfluoroolefins will become the next generation of immersion coolants.

[0006] Compared to other types of dielectric insulating liquids, including mineral oil, fluorinated liquids have many significant advantages: they are less toxic, non-flammable, and have the boiling point and thermal stability required for two-phase immersion cooling operations, making them more operator-friendly; in addition, electronic devices removed from fluorinated liquids are clean and dry, thus simplifying maintenance.

[0007] Immersion liquid cooling uses a coolant as the heat transfer medium, completely immersing the heat-generating components in the coolant for direct heat exchange. Depending on whether a phase change occurs in the coolant, immersion liquid cooling is divided into single-phase and two-phase immersion liquid cooling. Two-phase immersion liquid cooling exponentially improves the heat transfer efficiency of the coolant through boiling and condensation processes. It relies on the latent heat of vaporization of the coolant and is a more efficient cooling method than single-phase cooling.

[0008] Currently, there are few patents and publications on the preparation of perfluoro-3-methyl-2-pentene. US Patent 4377717 discloses a method for preparing perfluoro-2-methyl-2-pentene by gas-phase catalytic polymerization of hexafluoropropylene, using activated carbon as a catalyst, a reaction temperature of 410-420℃, a residence time of 13 seconds, a yield of 29.6%, and a selectivity of 64.5%. This method has a high reaction temperature and relatively low reaction conversion and selectivity.

[0009] CN107473929B discloses a method for preparing perfluoro-2-methyl-2-pentene and perfluoro-4-methyl-2-pentene by oligomerization of hexafluoropropylene. This method uses one, two, or more combinations of CsF, NaF, LiF, KF, and RbF as catalysts, and one, two, or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol dimethyl ether as solvents to achieve the co-production of perfluoro-2-methyl-2-pentene and perfluoro-4-methyl-2-pentene. However, this method is a batch reaction operation with low production efficiency.

[0010] CN1044786538B discloses a method for preparing perfluoro-2-methyl-2-pentene. This method uses a metal fluoride salt as the main catalyst, a guanidine compound as a co-catalyst, a polar aprotic solvent as the medium, and hexafluoropropylene as the raw material to prepare perfluoro-2-methyl-2-pentene. The yield of perfluoro-2-methyl-2-pentene using this method is approximately 95-98%, but the reaction time is relatively long, and the co-catalyst is difficult to recover and reuse.

[0011] US5387728 discloses a method for the liquid-phase catalytic polymerization of hexafluoropropylene to prepare perfluoro-4-methyl-2-pentene. In the presence of nonpolar solvents such as diethylene glycol diethyl ether, tetrahydrofuran, and acetonitrile, amine compounds such as N,N,N',N'-tetramethylethylenediamine and fluorides such as potassium fluoride and cesium fluoride are used as catalysts. The reaction is carried out under vigorous stirring at 30-40°C to obtain perfluoro-4-methyl-2-pentene. This method has a complex catalyst-solvent system, makes product separation difficult, and the dynamic seal is prone to leakage under high pressure.

[0012] CN1876611A discloses a method for preparing hexafluoropropylene dimer using acetonitrile (a nonpolar solvent) as the solvent and potassium thiocyanate as the catalyst at 10-50°C. This patent also discloses a reaction apparatus for preparing hexafluoropropylene dimer, in which a crank-connecting rod drives reciprocating motion, ensuring excellent material mixing while avoiding dynamic seals. Although this apparatus provides excellent material mixing, it is not suitable for industrial scale-up.

[0013] US4377717A discloses a method for producing perfluoro-2-methylpentene-2, which uses activated carbon as a catalyst and continuously passes perfluoropropylene vapor through the activated carbon at high temperature. The reaction temperature is 250-500℃, and the product yield is 65-75%. This method involves relatively high reaction temperatures and low yields.

[0014] CN113999362B discloses a rigid polyurethane foam and its preparation method, wherein perfluoro-3-methyl-2-pentene is used as a low-conductivity additive and polyisocyanate is emulsified by high-speed stirring to form a stable fluorinated liquid two-phase mixture. This patent does not involve a method for preparing perfluoro-3-methyl-2-pentene.

[0015] CN111647191B discloses a low-conductivity blowing agent composition and a rigid polyurethane foam prepared therefrom, wherein the blowing agent composition comprises cyclopentane, 1,1,1,2,2,3-hexafluoropropane, and perfluoro-3-methyl-2-pentene. However, this patent does not disclose a method for preparing perfluoro-3-methyl-2-pentene.

[0016] CN116004331A discloses a combined solvent and its application. The solvent, formulated with one or more of perfluoro-3-methyl-2-pentene, perfluoro-2-methyl-2-pentene, and (Z)-perfluoro-3-methyl-2-pentene and dichloroethylene, not only exhibits good dissolution and removal capabilities for organic contaminants such as mineral oil, synthetic oil, rosin flux, and silicone oil, but also demonstrates good compatibility with rubber and plastic materials, without causing swelling of the material matrix and affecting the normal use of electronic devices. However, this patent does not disclose a method for preparing perfluoro-3-methyl-2-pentene. Summary of the Invention

[0017] The purpose of this invention is to provide a method for preparing perfluoro-3-methyl-2-pentene. This method has advantages such as low synthesis cost, green and environmentally friendly, non-toxic, and can be mass-produced. The perfluoro-3-methyl-2-pentene produced can be used as a liquid cooling data center coolant.

[0018] The first aspect of this invention provides a method for preparing perfluoro-3-methyl-2-pentene, comprising the following steps:

[0019] In the presence of a catalyst, tetrafluoroethylene is heated to undergo a tetrafluoroethylene trimerization reaction. After the reaction is complete, the resulting gaseous product is condensed and distilled to obtain perfluoro-3-methyl-2-pentene. The catalyst is a fluoride salt catalyst.

[0020] Tetrafluoroethylene undergoes anionic polymerization under the catalysis of fluoride salts, resulting in a tetrafluoroethylene trimerization reaction to produce perfluoro-3-methyl-2-pentene. The specific reaction formula is as follows:

[0021]

[0022] Preferably, the fluoride salt catalyst is a fluorinated quaternary ammonium salt catalyst or a fluorinated chloride salt catalyst, with a fluorinated quaternary ammonium salt catalyst being more preferred. The fluoride ions in the fluorinated quaternary ammonium salt catalyst are more active than those in other catalysts, resulting in higher conversion rates of the feedstock and higher selectivity for the target product.

[0023] Preferably, the fluorinated quaternary ammonium salt catalyst is prepared by the following method:

[0024] The carrier was impregnated with a quaternary ammonium salt solution and filtered to obtain a quaternary ammonium salt catalyst precursor. The quaternary ammonium salt catalyst precursor was then fluorinated to obtain the fluorinated quaternary ammonium salt catalyst.

[0025] Preferably, the quaternary ammonium salt is a quaternary ammonium chloride, including at least one of tetrabutylammonium chloride, tetrabutylammonium bromide, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, trimethylhexadecylammonium chloride, trimethylhexadecylammonium bromide, trioctylmethylammonium chloride, trioctylmethylammonium fluoride, tetramethylammonium fluoride, tetrabutylammonium fluoride, or tetraethylammonium fluoride. Using a quaternary ammonium chloride as the active component in the catalyst preparation allows for a higher reaction rate in the tetrafluoroethylene trimerization reaction.

[0026] Preferably, the solvent for the quaternary ammonium salt solution is at least one of methanol, ethanol, acetonitrile, or methyl tert-butyl ether.

[0027] Preferably, the carrier is alumina or activated carbon. Alumina carrier is preferred.

[0028] Preferably, the alumina particles have a diameter of 0.04-5 mm and a specific surface area of ​​10-200 m². 2 / g. More preferably, the diameter of the alumina particles is 0.5-1mm.

[0029] Preferably, the molar ratio of the quaternary ammonium salt to the support is 0.05-0.5:1. If the molar ratio of the quaternary ammonium salt to the support is too low, the content of the active component is low, and the reaction efficiency is low; if the molar ratio is too high, the support surface is easily saturated, the support cannot play a synergistic role, and the product yield will decrease. This invention controls the molar ratio of the quaternary ammonium salt to the support within the above range, which enables the tetrafluoroethylene trimerization reaction to have high reaction efficiency and a high yield of the target product.

[0030] Preferably, the impregnation temperature is 20-50°C and the impregnation time is 1-5 hours. More preferably, the impregnation temperature is 40-50°C and the impregnation time is 2-3 hours.

[0031] Preferably, hydrogen fluoride gas is used to completely fluorinate the quaternary ammonium salt catalyst precursor. To ensure complete fluorination of the catalyst precursor, excess hydrogen fluoride gas can be used during the reaction. The fully fluorinated quaternary ammonium salt catalyst has better reactivity, resulting in higher conversion rates of the raw materials and higher selectivity for the target product.

[0032] Preferably, the fluorination is carried out in a fixed-bed reactor, and the specific fluorination process is as follows: First, the quaternary ammonium salt catalyst precursor is filled into the fixed-bed reactor, then the temperature is raised to 120-150°C, and then hydrogen fluoride gas is introduced to fluorinate the quaternary ammonium salt catalyst precursor. The fluorination temperature is 150-180°C, the residence time of the hydrogen fluoride gas in the catalyst bed is 2-5 minutes, and the hydrogen fluoride gas introduction time is 2-3 hours. Under these conditions, the quaternary ammonium salt catalyst precursor (including the support) can be completely fluorinated. Complete fluorination is considered to be achieved when no water condenses in the tail gas during the catalyst fluorination process.

[0033] More preferably, the fluorination temperature is 160-170°C.

[0034] Preferably, before fluorinating the quaternary ammonium salt catalyst precursor, the temperature of the fixed-bed reactor is raised to 80-100°C and purged with nitrogen for 20-30 minutes to remove impurities, moisture, and a small amount of residual methanol from the catalyst surface.

[0035] Preferably, after fluorination, the flow of hydrogen fluoride gas is stopped, and the remaining hydrogen fluoride gas is replaced with nitrogen gas before cooling and storing. Replacing the remaining HF with nitrogen gas after fluorination can prevent HF from interfering with subsequent reactions.

[0036] Preferably, when using the fluorinated quaternary ammonium salt catalyst prepared according to the present invention to carry out the tetrafluoroethylene trimerization reaction, the fluorinated quaternary ammonium salt catalyst is first filled into the reactor, and then the reactor is heated. During the heating process, a small flow of nitrogen gas is introduced to remove the residual hydrogen fluoride on the catalyst surface. After reaching the reaction temperature, the nitrogen gas is turned off, and tetrafluoroethylene is introduced to carry out the tetrafluoroethylene trimerization reaction.

[0037] Preferably, the mass ratio of the fluoride salt catalyst to tetrafluoroethylene is 0.05-0.5:1.

[0038] Preferably, the tetrafluoroethylene trimerization reaction is carried out in a fixed-bed reactor.

[0039] Preferably, the temperature of the tetrafluoroethylene trimerization reaction is 60-120℃, the pressure is 0.2-1.5 MPa, and the residence time of tetrafluoroethylene is 10-60 min. This invention controls the conditions of the tetrafluoroethylene trimerization reaction within the above range, resulting in a high yield of the target product. More preferably, the temperature of the tetrafluoroethylene trimerization reaction is 70-90℃, the pressure is 0.2-0.4 MPa, and the residence time of tetrafluoroethylene is 10-20 min.

[0040] A second aspect of the present invention provides perfluoro-3-methyl-2-pentene prepared by the above preparation method.

[0041] The third aspect of this invention provides the application of the aforementioned perfluoro-3-methyl-2-pentene as a liquid-cooled data center coolant. The perfluoro-3-methyl-2-pentene of this invention has similar coolant properties to perfluoro-2-methyl-2-pentene and perfluoro-4-methyl-2-pentene, and possesses advantages such as low synthesis cost, environmental friendliness, and non-toxicity, making it suitable for use as a fluorinated fluid in data center phase change immersion liquid cooling systems.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] (1) This invention employs a fluorinated salt catalyst with high catalytic activity, especially a fluorinated quaternary ammonium salt catalyst, to catalyze the tetrafluoroethylene trimerization reaction to prepare perfluoro-3-methyl-2-pentene. By controlling the reaction conditions, both the conversion rate of tetrafluoroethylene and the selectivity of the target product are high. The method of this invention can achieve a tetrafluoroethylene conversion rate of over 98% and a perfluoro-3-methyl-2-pentene selectivity of over 86%.

[0044] (2) The present invention prepares perfluoro-3-methyl-2-pentene by the trimerization reaction of tetrafluoroethylene. Compared with the general method of tetrafluoroethylene oligomerization, it has the advantages of high yield of perfluoro-3-methyl-2-pentene, long catalyst life, no solvent, less waste, and simple operation. Detailed Implementation

[0045] Example 1

[0046] Dissolve 115g of tetramethylammonium chloride in 200g of anhydrous methanol, add 142g of 1-3mm alumina balls, maintain the impregnation temperature at 45℃, and impregnate for 2.5h. After impregnation, filter out excess methanol using a funnel, and pour the alumina balls into a tubular reactor. Turn on the heater, control the bed temperature at 90℃, and simultaneously introduce nitrogen gas at a flow rate of 100mL / min. Maintain the temperature at 90℃ for 30min, then raise the bed temperature to 130℃, stop the nitrogen flow, and switch to anhydrous HF gas for fluorination. Control the HF residence time at 5min, the bed temperature at 162℃, and the fluorination time for 2.5h. After the tail gas is condensed anhydrous, fluorination is considered complete. After fluorination, switch to nitrogen gas for purging, maintain the nitrogen flow rate at 100mL / min, and simultaneously lower the reactor bed temperature to 80℃. When the temperature reaches 80℃, turn off the nitrogen gas and switch to tetrafluoroethylene feed, controlling the tetrafluoroethylene residence time to 12min. Open the back pressure valve at the reactor outlet to maintain the reactor pressure at 0.25 MPa. The exhaust gas is condensed using a -15°C refrigeration unit, and the condensate is then distilled to obtain the target product, perfluoro-3-methyl-2-pentene. The collected condensate is analyzed by gas chromatography; the data are shown in Table 1.

[0047] Example 2

[0048] 291g of tetrabutylammonium chloride was dissolved in 208g of anhydrous methanol, and 146g of 1-3mm alumina balls were added. The impregnation temperature was maintained at 45℃ for 3 hours. After impregnation, excess methanol was filtered out using a funnel, and the alumina balls were poured into a tubular reactor. Heating was started, and the bed temperature was controlled at 90℃. Nitrogen gas was simultaneously introduced at a flow rate of 100mL / min and maintained at 90℃ for 30 minutes. The bed temperature was then raised to 100℃, and the nitrogen supply was stopped. Anhydrous HF gas was then switched to fluorination. The HF residence time was controlled at 5 minutes, the bed temperature at 140℃, and the fluorination time at 2.5 hours. Fluorination was considered complete after the tail gas was condensed anhydrous. After fluorination, nitrogen gas was switched to purging at a flow rate of 100mL / min, and the reactor bed temperature was reduced to 85℃. When the temperature reached 85℃, the nitrogen supply was stopped, and tetrafluoroethylene was fed, with the tetrafluoroethylene residence time controlled at 15 minutes. Open the back pressure valve at the reactor outlet to maintain the reactor pressure at 0.25 MPa. The exhaust gas is condensed using a -15°C refrigeration unit, and the condensate is then distilled to obtain the target product, perfluoro-3-methyl-2-pentene. The collected condensate is analyzed by gas chromatography; the data are shown in Table 1.

[0049] Example 3

[0050] 54g of tetramethylammonium bromide was dissolved in 251g of anhydrous methanol, and 189g of 1-3mm alumina balls were added. The impregnation temperature was maintained at 50℃ for 3 hours. After impregnation, excess methanol was filtered out using a funnel, and the alumina balls were poured into a tubular reactor. Heating was started, and the bed temperature was controlled at 95℃. Nitrogen gas was simultaneously introduced at a flow rate of 100mL / min and maintained at 90℃ for 30 minutes. The bed temperature was then raised to 140℃, and the nitrogen flow was stopped. Anhydrous HF gas was then switched to fluorination. The HF residence time was controlled at 7 minutes, the bed temperature at 180℃, and the fluorination time at 2.5 hours. Fluorination was considered complete after the tail gas was condensed anhydrous. After fluorination, nitrogen gas was switched to purging at a flow rate of 100mL / min, and the reactor bed temperature was reduced to 90℃. When the temperature reached 90℃, the nitrogen flow was stopped, and tetrafluoroethylene was fed, with the tetrafluoroethylene residence time controlled at 12 minutes. The back pressure valve at the reactor outlet was opened to maintain the reactor pressure at 0.4 MPa. The exhaust gas was condensed using a -15°C refrigeration unit, and the condensate was then distilled to obtain the target product, perfluoro-3-methyl-2-pentene. The collected condensate was analyzed by gas chromatography, and the data are shown in Table 1.

[0051] Comparative Example 1

[0052] Add 142g of 1-3mm alumina balls to 200g of anhydrous methanol, maintaining the impregnation temperature at 45℃ for 2.5h. After impregnation, filter out excess methanol using a funnel and pour the alumina balls into a tubular reactor. Turn on the heater, controlling the bed temperature at 90℃, and simultaneously introduce nitrogen gas at a flow rate of 100mL / min. Maintain the temperature at 90℃ for 30min, then raise the bed temperature to 130℃, stop the nitrogen flow, and switch to anhydrous HF gas for fluorination. Control the HF residence time at 5min, the bed temperature at 162℃, and the fluorination time at 2.5h. After the tail gas condenses anhydrously, fluorination is considered complete. After fluorination, switch to nitrogen gas for purging, maintaining a nitrogen flow rate of 100mL / min, while simultaneously lowering the reactor bed temperature to 80℃. When the temperature reaches 80℃, turn off the nitrogen gas and switch to tetrafluoroethylene (TEFE) feed, controlling the TFE residence time to 12min. Open the back pressure valve at the reactor outlet to maintain the reactor pressure at 0.25 MPa. The exhaust gas is condensed using a -15°C refrigeration unit, and the condensate is then distilled to obtain the target product, perfluoro-3-methyl-2-pentene. The collected condensate is analyzed by gas chromatography; the data are shown in Table 1.

[0053] Comparative Example 2

[0054] Dissolve 58g of potassium fluoride in 500g of anhydrous methanol, add 300g of 1-3mm alumina balls, maintain the impregnation temperature at 45℃, and impregnate for 2.5h. After impregnation, filter out excess methanol using a funnel, and pour the alumina balls into a tubular reactor. Turn on the heater, control the bed temperature at 90℃, and simultaneously introduce nitrogen gas at a flow rate of 100mL / min. Maintain the temperature at 90℃ for 30min, then raise the bed temperature to 130℃, stop the nitrogen flow, and switch to anhydrous HF gas for fluorination. Control the HF residence time at 5min, the bed temperature at 162℃, and the fluorination time for 2.5h. After the tail gas is condensed anhydrous, fluorination is considered complete. After fluorination, switch to nitrogen gas for purging, maintain the nitrogen flow rate at 100mL / min, and simultaneously lower the reactor bed temperature to 80℃. When the temperature reaches 80℃, turn off the nitrogen gas and switch to tetrafluoroethylene feed, controlling the tetrafluoroethylene residence time to 12min. Open the back pressure valve at the reactor outlet to maintain the reactor pressure at 0.25 MPa. The exhaust gas is condensed using a -15°C refrigeration unit, and the condensate is then distilled to obtain the target product, perfluoro-3-methyl-2-pentene. The collected condensate is analyzed by gas chromatography; the data are shown in Table 1.

[0055] Table 1

[0056] .

Claims

1. A process for the preparation of perfluoro-3-methyl-2-pentene, characterized in that, The method comprises the following steps: The tetrafluoroethylene is heated for trimerization under the action of a catalyst, and after the reaction is completed, the obtained gaseous product is condensed and rectified to obtain perfluoro-3-methyl-2-pentene; wherein the catalyst is a fluorinated quaternary ammonium salt catalyst, and the fluorinated quaternary ammonium salt catalyst is prepared by the following method: The carrier is impregnated with a quaternary ammonium salt solution, filtered to obtain a quaternary ammonium salt catalyst precursor, and then the quaternary ammonium salt catalyst precursor is completely fluorinated with hydrogen fluoride gas to obtain the fluorinated quaternary ammonium salt catalyst; The quaternary ammonium salt is at least one of tetrabutylammonium chloride, tetrabutylammonium bromide, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, trimethylhexadecylammonium chloride, trimethylhexadecylammonium bromide, tricaprylylmethylammonium chloride, tricaprylylmethylammonium fluoride, tetramethylammonium fluoride, tetrabutylammonium fluoride or tetraethylammonium fluoride; The carrier is alumina; The molar ratio of the quaternary ammonium salt to the carrier is 0.05-0.5:1; The mass ratio of the fluorinated quaternary ammonium salt catalyst to tetrafluoroethylene is 0.05-0.5:1; The temperature of the tetrafluoroethylene trimerization reaction is 60-120℃, and the pressure is 0.2-1.5 MPa.

2. The method of claim 1, wherein, The fluorination is carried out in a fixed bed reactor, and the fluorination process is as follows: first, the quaternary ammonium salt catalyst precursor is filled into the fixed bed reactor, then the temperature is raised to 120-150℃, then hydrogen fluoride gas is introduced to fluorinate the quaternary ammonium salt catalyst precursor, the fluorination temperature is 150-180℃, the residence time of the hydrogen fluoride gas in the catalyst bed is 2-5 min, and the introduction time of the hydrogen fluoride gas is 2-3 h.

3. The method of claim 1, wherein, The residence time of tetrafluoroethylene in the tetrafluoroethylene trimerization reaction is 10-60 min.

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